3rd Router - LAN - 192.168.33.0
I have tried a Belkin F5D7230v4 and now a WRT54gv6
tried to set the WAN IP statically (both in and out of the RV042's DHCP range)to the 192.168.2.0 network and also have tried to allow dynamic allocation . I have tried putting the WRT54G in router and gateway modes. I used RIP and also tried static routes. With the new firrmware I tried using the multiple subnet setting with a 192.168.33.0/255.255.255.0 and also 192.168.33.1/255.255.255.0.

In all cases this network works fine for anywhere between 5 minutes to an hour, sometimes more, but rarely. Then the RV042 loses its connection to this router. Please note also that I have switched out the RV042 to eliminate the possibility of a bad port and also replaced my CAT5 cables as well.

I know I am probably missing something obvious here, as this isn't my main gig, but I think I have a pretty good grasp on things. Any help is greatly appreciated.

2 more tests to determine which device the problem lies. 1) switch the ports router 2 and router 3 use (this way you can determine if its a port based problem). If the problem follows router 3 then move router 3 behind router 2 just to test uptime. If the problem persists you know its router 3 for sure. If the problem goes away then we have a much more perplexing issue that will probably take a packet sniffer and some thought to figure out.